Foam inhibited emulsifiable mineral oil composition



Patented Mar. 19, 1953 3 FGAIW ENHEBHTED Elt iULSTFiABLE MINERAL 01LThis invention relates to emulsifiable mineral oil compositions,sometimes referred to as soluble oils, and to oil-in-water emulsionsprepared from such compositions, and in particular to an additivematerial for use in such compositions and emulsions in order to inhibitfoaming of the emulsion.

It is well known in the art to prepare mixtures of mineral oil andemulsifying agents which are capable of being emulsified in Water toform emulsions for use as cutting fluids, metal rolling oils, textileoils, etc. A problem that is sometimes encountered in the use of suchemulsions is the formation of foams which interfere with the handling ofthe emulsion. It has been proposed in the prior art to add vegetable ormineral waxes to the compositions in order to inhibit such foaming.However, the foam-inhibiting additives which have been preparedpreviously do not provide satisfactory results in all cases. Whenconditions are encountered which result in a strong foaming tendency,the additives employed in the prior art are sometimes inadequate toprevent foaming, at least when they are used in the relatively smallamounts which are usually desired to be used. V

The present invention provides a composition contain: ing, asfoam-inhibiting additives, partially oxidized petroleum microcrystallinewaxes. It has been found that these oxidized waxes provide superiorfoam-inhibition to that which is obtained with the unoxidizedmicrocrystalline waxes which have been employed in the prior art.

The emulsifiable compositions and emulsions to which the foam-inhibitingadditive is added contains mineral oil and emulsifying agent, andpreferably contains mineral oil, carboxylic acid salts and sulfonic acidsalts. The mineral oil is employed in the amount of 70 to 90 weightpercent of the total composition on the anhydrous basis, and is usuallya lubricating oil distillate having viscosity within the range from 50Saybolt Universal seconds at 100 F. to 300 Saybolt Universal seconds at100 F. The foam inhibiting additives according to the invention areparticularly advantageous for use in emulsifiable mineral oilcompositions which contain mineral oil having Saybolt Universalviscosity in the range from 50 to 150 Saybolt Universal seconds at 100F. The unoxidized microcrystalline waxes on the other hand are noteffective in such compositions, apparently because of an adverse effectof the relatively low viscosity mineral oil on the foaminhibitingactivity of the microcrystalline wax.

The invention is generally applicable to the known soluble oilscontaining mineral oil and containing soaps as emulsifiers. The knownsoaps for this use are generally suitable here. A preferred emulsifyingagent is one containing both carboxylic acid salts and sulfonic acidsalts.

Such carboxylic acid salts are in one embodiment employed in the amountfrom 6 to 12 weight percent of the total composition on the anhydrousbasis, and are usually alkali metal or aliphatic amine salts ofaliphatic or cycloaliphatic carboxylic acids, which acids have 12 to 30carbon atoms per molecule. The carboxylic acid salts are conventionalcomponents of emulsifiable mineral oil compositions, and any of theknown salts can be employed. Typical carboxylic acids for the formationof such salts are the fatty acids, petroleum naphthenic acids, acidsproduced by liquid phase partial oxidation of aliphatic or naphthenichydrocarbons, or of mixtures containing aliphatic and naphthenichydrocarbons, e.g. dearomatized petroleum fractions. In preferredembodiments of the invention, the carboxylic acid salts which areemployed constitute a mixture of salts of petroleum naphthenic acids andsalts of acids produced by liquid phase partial oxidation of asolvent-refined mixture of lubricating oil and low-melting wax, i.e. waxhaving melting point below F. Such compositions are described in moredetail in Patent No. 2,797,197 which issued on June 25, 1957, to NormanThompson and Willard K. Parcells.

The sulfonic acid salts which are employed in the composition in oneembodiment are also conventional components of emulsifiable mineral oilcompositions. Preferably the average molecular weight of the sulfonicacids which are employed to make the salts is within the approximaterange from 425 to 525. Alkali metal or aliphatic amine salts of thesulfonic acids can be employed. The sulfonic acids are generallyproduced by the sulfonation of a solvent-refined petroleum lubricatingoil in a manner which is well known in the art.

Suitable alkali metals and amines for the sulfonic and carboxylic saltsinclude those which are known in the art for soluble oil emulsifyingagents, e.g. sodium, potassium, lithium, isopropylamine,isopropanolamine, triethanolarnine, etc. Usually the amine has 2 to 12carbon ate-ms per molecule.

The total amount of emulsifying agent in the composition according tothe invention is preferably in the range from 7.5 to 15 weight percenton the anhydrous basis.

The oxidized microcrystalline wax employed in the composition of theinvention is obtained by the liquid phase partial oxidation of petroleummicrocrystalline wax. Such wax usually has melting point in theapproximate range from 145 to 200 F. The procedure for partiallyoxidizing microcrystalline wax is well known in the art and usuallyinvolves blowing air or oxygen through the molten wax at a temperaturein the range from 250 to 400 F. in the presentce of a metallic catalyst,for example manganese salts of petroleum naphthenic acids. Thesaponification number of the oxidized microcrystalline wax which isemployed is preferably at least 40 mg. of KOH per gram. The upper limitis not critical but preferably the saponification number is in theapproximate range from 40 to mg. of KOH per gram, although othersaponification numbers can be used in some cases.

The oxidized microcrystalline wax is present in relatively small amountin the emulsifiable composition, e.g. in the range from 0.05 to 1.0weight percent based on the total composition on the anhydrous basis. Inorder to obtain the foam inhibiting properties, it is necessary thatthis material be obtained from a microcrystalline wax, rather than fromlower melting wax. Amounts of the oxidized microcrystalline wax greaterthan 1.0 weight percent are avoided in order to avoid detrimental effecton the low temperature properties of the composition.

Frequently, the emulsifiable mineral oil compositions contain, inaddition to the components referred to previously, a coupling agent ormutual solvent which improves the stability of the emulsifiablecomposition prior to emulsification or of the emulsion producedtherefrom or both. Many mutual solvents are known in the prior art, andthe known mutual solvents are generally suitable for use according tothe invention.

The emulsifiable mineral oil composition frequently contains a smallamount of water, usually in the range from 1 to 5 weight percent of thetotal composition prior to emulsification.

Preferably the emulsifiable mineral oil composition according to theinvention contains a small amount of free alkali, e.g. in the range from0.01 to 0.2 weight percent as sodium hydroxide. It is within the scopeof the invention, however, to prepare emulsifiable compositions whichare on the acid side rather than the alkaline side.

In compositions which are on the alkaline side, the carboxylic acids inthe oxidized microcrystalline wax are in the salt form, whereas insoluble oils which are on the acid side at least a portion of thecarboxylic acids in the oxidized microcrystalline wax are in the freeacid form. In either event the oxidized microcrystalline wax iseffective as a foam inhibiting additive.

In one embodiment of the invention, the oxidized microcrystalline wax isemployed in conjunction with a polymer of a vinyl aromatic compound suchas styrene. The compositions containing such polymers and oxidizedmicrocrystalline Wax are disclosed in application Serial No. 694,917filed November 7, 1957 by Samuel E. Jolly now US. Patent 2,944,039. Atypical preparation of such composition involves the followingprocedure. A partially oxidized microcrystalline wax havingsaponification number of 85.7 mg. of KOH per gram and Saybolt Universalviscosity at 210 F. of 552 seconds is prepared by partial oxidation ofmicrocrystalline wax at 250 to 270 F. with air for 203.5 hours in thepresence of manganese naphthenate in amount such that the oxidationmixture contains 0.04 weight percent of manganese. 250 grams of thepartially oxidized wax are heated together with 100 ml. of xylene underrefluxing conditions with mechanical stirring. To the heated solution ofoxidized wax in xylene, 250 grams of styrene containing 2.5 grams ofditertiarybutyl peroxide are added dropwise with stirring. The reactionmixture is refluxed for 5 hours. The stirrer and condenser are thenremoved and unreacted styrene and xylene are stripped off. 467.5 gramsof a homogeneous product having saponification number of 43.8 mg. of KOHper gram are left as residue. This product can be employed as themixture of oxidized wax and polymer in the composition according to theinvention.

In one embodiment, the foam inhibitor is obtained by admixing preformedpolymer of a vinyl aromatic compound with oxidized wax. In anotherembodiment, the inhibitor is obtained by polymerizing a mixture of avinyl aromatic monomer and oxidized wax. The amount of oxidized wax inthe mixture with monomer or polymer is preferably in the range from 20to 9.0, more preferably at least 50, weight percent of the mixture. Theamount of oxidized wax in the emulsifiable composition in thisembodiment is preferably in the range from 0.05 to 1.0 weight percent onthe anhydrous basis, and the total amount of oxidized wax and vinylaromatic polymer is preferably in the range from 0.1 .to 1.5 weightpercent on the anhydrous basis. The vinyl aromatic monomers and polymersdisclosed in the Jolly application referred to above are generallysuitable for use according to the present invention.

Typically, the emulsiflable compositions of the invention are emulsifiedby agitating with hard or soft water at a temperature in the range from45 to 180 F. to give emulsions containing 1 to weight percent of thenonaqueous constituents. However, other proportions and procedures canbe employed.

The following examples illustrate the invention:

Example 1 The following composition is prepared:

Mineral oil 84.55

The mineral oil is mainly a distillate from naphthenic base crude, whichdistillate has Saybolt Universal viscosity of 110 seconds at 100 F. Themineral oil also includes Mid-Continent distillate lubricating oil, ofabout SUS/ 100 F. viscosity, introduced with the sulfonic acid salts,the amount of the latter mineral oil being about 60% of .the amount ofsulfonic acid salts.

The carboxylic acid salts in the composition are a mixture of sodiumnaphthenates and sodium salts of carboxylic acids produced by liquidphase partial oxidation of a Mid-Continent lubricating oil containingabout 40% 0f low-melting wax, i.e. about 40% of material which iscrystallizable from methyl ethyl ketone at 0 F. and which has meltingpoint below 100 F. The waxcontaining oil has Saybolt Universal viscosityat 100 F. of about 136 seconds and conforms generally to the foots oildescribed in Patent No. 2,797,197, referred to previously. The partialoxidation is conducted in the manner described in that patent andresults in a product having saponification number of about 75 mg. of KOHper gram.

The naphthenic acids from which the sodium naphthenates are preparedhave 10% point of about 350 F., 95% point of about 550 F. indistillation at 2 mm. of Hg absolute, and have saponification number ofabout 140 mg. of KOl-I per gram. Two volumes of the naphthenic acids areemployed per volume of the partially oxidized foots oil havingsaponification number of 75 mg. of KOH per gram.

The sulfonic acid salts used in the composition are obtained bycontacting an raflinate from furfural refining of lubricating oil withabout 14 pounds of anhydrous SO per barrel of oil at ambienttemperature, separating oil-insoluble Sulfonic acids from the product,extracting sodium salts of the oil-soluble sulfonic acids from the oilwith aqueous isopropanol, and stripping off solvent to obtain the sodiumsalts for use in the composition. The sulfonic acids have averagemolecular Weight of about 450.

The oxidized rnicrowax employed in the above composition is obtained bythe liquid phase partial oxidation of petroleum rnicrocrystalline waxhaving melting point of 178 F. The partial oxidation is conducted atabout 260 F. by blowing with air for about 200 hours in the presence of0.04 weight percent of manganese in the form of manganese naphthenate.The saponification number of the oxidized Wax is about 85 mg. of KOH pergram.

The emulsifiable composition is prepared by mixing the oxidized wax withthe mineral oil at about 190 F.

to dissolve the oxidized wax in the oil, which is then cooled to aboutF. and is admixed with the petroleum naphthenic acids, the sulfonic acidsalts and the oxidized foots oil, and with 50 B. sodium hydroxide inamount to neutralize the acids and provide the indicated amount of freealkali. The 2-methyl pentanediol as coupling agent is incorporated inthe indicated amount, and the water content is adjusted to the indicatedlevel.

A 2% emulsion of this composition in tap water containing 4050 parts permillion total hardness is prepared at 63 F. and tested forfoam-resisting characteristics by the following procedure: A 200 ml.sample is blown with air for 5 minutes in a ml. cylinder at roomtemperature. The air is supplied at a constant gauge pressure of 34inches of water to a one-inch diameter spherical gas diffuser stone, asspecified in A.S.T.M. Test D892-46T, through which it passes into theemulsion in the bottom of the cylinder. The emulsion passes the testsince the foam which forms does not overflow the cylinder, and breakscompletely within 15 seconds after shutting off the air supply.

To compare the oxidized microwax with an unoxidized microwax, acomposition is prepared by identical procedure except that themicrocrystalline wax is not oxidized but is employed directly in theunoxidized state as the foam inhibitor. In this case, the 2% emulsionoverflows the 1000 ml. cylinder almost immediately upon introduction ofair, and persists for more than seconds after the air is shut oif.

This example shows the superiority of the oxidized wax to the unoxidizedwax as a foam inhibitor in mineral oil emulsions.

Exomple 2 The procedure of Example 1 is repeated, employing however afoam inhibitor obtained by polymerizing styrene in the presence ofoxidized microcrystalline wax, in place of the oxidized microcrystallinewax of Example 1. The concentration of foam inhibitor is the same as inExample 1. The 2% emulsion passes the test described in Example 1. Noneof the foam inhibitor is deposited on the wall of the cylinder, whereasin Example 1, slight deposition of oxidized wax on the wall of thecylinder occurs during the air blowing.

This example shows that the polystyrene and oxidized wax compositionprovides the same improved foam suppression as the oxidized wax alone,and also is less subject to the precipitation of solid material.

The oxidized wax can be added to the emulsifiable composition or to theemulsion at any desired stage in the preparation. In cases where it isdesired to add the oxidized Wax to an otherwise finished emulsifiablecomposition containing oil, soap and frequently small amounts ofcoupling agent and water, it is preferred to first dissolve the oxidizedwax in a relatively small amount of oil to form a concentrated solution,which is then added to the emulsifiable composition in relatively smallamount to provide the desired concentration of oxidized wax withoutunduly increasing the oil content. By adding a previously formedsolution in oil, rather than the oxidized wax itself, to theemulsifiable composition, temperatures considerably below the meltingpoint of the oxidized wax can be employed in the addition, therebyavoiding excessive vaporization of coupling agent or water from theemulsifi able composition during the addition. Any other suitable methodof addition can be employed.

The invention claimed is:

1. A foam-inhibited emulsifiable mineral oil composition comprising thefollowing components in the indicated ranges of proportions:

Mineral oil said carboxylic acid salts being selected from the groupconsisting of alkali metal and aliphatic amine salts of carboxylic acidsselected from the group consisting of aliphatic and cycloaliphaticcarboxylic acids having 12 to 30 carbon atoms per molecule, saidsulfonic acid salts being selected from the group consisting of alkalimetal and aliphatic amine salts of petroleum sulfonic acids, saidoxidized microwax being the product of liquid phase partial oxidation ofpetroleum microcrystalline wax and having a saponification number of atleast 40 mg. of KOH per gram, and said mineral oil being a petroleumlubricating oil having Saybolt Universal viscosity at 100 F. in therange from 50 to 300 seconds.

2. The composition according to claim 1 wherein the composition contains0.1 to 1.5 weight percent of the product obtained by contactingpartially oxidized petroleum microcrystalline wax with a monovinylaromatic compound having the following formula:

where R is selected from the group consisting of hydrogen, methyl andethyl radicals, A is selected from the group consisting of hydrogen,halogen and alkyl radicals having 1 to 3 carbon atoms inclusive, and Bis selected from the group consisting of hydrogen, halogen and alkylradicals having 1 to 3 carbon atoms inclusive, the amount of oxidizedwax in the resulting mixture being in the range from 20 to weightpercent of the mixture, said contacting being performed under conditionsfor polymerization of said'monovinyl aromatic compound, and the amountof oxidized wax in said product contained in said composition being inthe range from 0.05 to 1.0 Weight percent of said composition.

References Cited in the file of this patent UNITED STATES PATENTS2,340,035 Zimmer et al. Jan. 25, 1944 2,545,677 Sperry Mar. 20, 19512,881,140 Schrum Apr. 7, 1959 2,944,039 Jolly July 5, 1960

1. A FOAM-INHIBITED EMULSIFIABLE MINERAL OIL COMPOSITION COMPRISING THEFOLLOWING COMPONENTS IN THE INDICATED RANGES OF PROPORTIONS: